Resilient contact-pin assembly



United States Patent 7 3,251,018 RESILIENT CONTACT-PIN ASSEMBLY George K. Bennett, Bronxville, N.Y., assignor to The Psychological Corp., New York, N.Y., a corporation of New York Filed July 11, 1963, Ser. No. 294,435 1 Claim. '(Cl. 339-61) This invention relates generally to contact pin assemblies, particularly of the type intended for usein punchedcard readers and similar devices wherein information or data symbolized by perforations or punched holes in a card or by conductive markings on a card or sheet, governs the establishment of electrical circuits for controlling or programming the operation of an associated machine, or for feeding pulses corresponding to the sensed or read information into an associated computer or the like.

In existing punched-card readers, a card having perforations or punched holes located therein at locations corresponding to, or symbolizing information or data to be read, is manually placed on a supporting surface from Y which contact pins yieldably project at all of the possible locations of perforations in the card, and a vertically movable platen having a printed circuit or conductive plate on its lower surface is moved downwardly against the card on the supporting surface, either by manual actuation of a handle or by energization of a solenoid, so

that those contact pins at the locations of the perforations or punched holes project through the latter into engagement with the associated portions of the printed circuit or conductive plate on the platen to close the corresponding electrical circuits. In the contact-pin assemblies of existing card readers and the like, each of the contact pins is individually mounted in a bearing sleeve or other similar structure for limited vertical movement relative to the supporting surface, so that those contact pins which do not register with perforations or punched holes of the card can be depressed by the latter to lie flush with the supporting surface upon downward movement of the platen against the card. Further, in order to ensure that the pins aligned with punched holes of the card will project upwardly through such punched holes into contact with the printed circuit or conductive plate of the platen, individual springs act upwardly against the contact pins and urge the latter to positions Where the upper ends of the contact pins project above the supporting surface by a distance at least slightly greater than the thickness of the punched card. Since punched-card readers of the described character may have as many as 960 contact pins for correspondence with a similar number of possible locations of punched holes in the card to be read, it is apparent that the individual slidable mountings and springs for such a large number of contact pins result in a contact-pin assembly of complex construction which is costly to assemble, and which has many possibilities for failure during use or operation.

Accordingly, it is an object of this invention to provide a contact-pin assembly for use in punched card readers and other similar devices, and wherein such assembly is of simple construction, thereby to reduce its cost of manufacture, while ensuring reliable operation over along useful life.

In accordance with an aspect of this invention, a contact-pin assembly comprises a hollow housing, preferably of insulating material, having aligned bores extending through opposed walls thereof, contact pins extending through the interior of the housing and being axially guided in said bores to project from the housing at the opposed walls thereof, and a body of molded elastomeric material filling the interior of the housing and closely adhering around the contact pins in the latter so as to yield- 3,251,018 Patented May 10, 1966 ably resist axial displacement of the contact pins from normal positions where ends of the pins project a relatively small distance beyond one of the opposed walls.

In order to ensure that the contact pins will not move axially independently of elastic deformation of the molded body of elastomeric material within the housing, the contact pins are preferably formed with cross-sectional configurations that are non-uniform along the length thereof, for example, by being provided with circumferentially extending grooves, flanges or the like at axially spaced locations.

In accordance with the method embodying this invention, a-contact-pin assembly having the characteristics described above is produced by forming a hollow housing with aligned bores in opposed walls thereof, for example, in the top and bottom walls, while a side wall of the housing is provided with one or more openings, inserting the contact pins through the aligned bores of the top and bottom walls of the housing so as to be supported and axially located by the latter, disposing the housing so that the opening or openings in the side wall is at the top, and pouring into the interior of the housing, through the opening or openings, a liquid latex or ela'stomeric material which fills the interior of the housing, such liquid latex or elastomeric material setting within the housing, for example, by reason of a catalyst included therein, and thereafter closely adhering to, and yieldably holding the contact pins against axial displacement.

The above, and other objects, features and advantages of the invention, will be apparent in the following detailed description of illustrative embodiments thereof which is to be read in connection with the accompanying drawing, forming a part hereof, and wherein:

FIG. 1 is a diagrammatic view illustrating a punched card reader having a contact-pin assembly in accordance with an embodiment of this invention;

FIG. 2 is a fragmentary, enlarged sectional view of an end portion of the contact-pin assembly of FIG. 1, and illustrating the condition of the latter during operation of the punched card reader;

FIG. 3 is a fragmentary sectional view illustrating the operation of the contact-pin assembly embodying this invention in a device for reading or sensing conductive markings applied to a card or sheet;

FIG. 4-is a sectional view illustrating-the housing of the contact-pin assembly during an initial phase in the production of the assembly in accordance with this invention;

FIG. 5 is a fragmentary elevational view of the top wall of the housing of the contact-pin assembly;

' FIG. 6 is a sectional view similar to that of FIG. 4, a

but illustrating the condition of the contact-pin assembly upon molding of its elastomeric body;

FIG. 7 is an elevational view of a modified form of contact pin; and e FIG. 8 is an elevational view of another modified fo of contact pin.

Referring to the drawings in detail, and initially to FIG. 1 thereof, it will be seen that the present invention is there shown applied to a contact-pin assembly 10 for a punchedcard reader 11. The reader 11, which, as such, forms no part of the present invention, generally includes a table or base 12 defining a supporting surface 13. The contact-pin assembly 10 is mounted in base 12 so as to be substantially flush-with surface 13 and thus covered by a perforated card C which is manually placed on the supporting surface. A platen 14, which may be formed of a phenolic-resin-impregnated linen laminate or an epoxy-resin glass-cloth laminate, is mounted above supporting surface 13 for vertical movement toward and prise a spindle extending upwardly therefrom and being slidable in a bearing structure 16 carried by a fixed frame 17. During manual placement of the card C on supporting surface 13, and during removal of the punched card following the reading thereof, platen 14 is elevated, as shown on FIG. 1, for example, by manual actuation of a handle 18 pivotally mounted on the frame 17, as at 19, and connected through a link 20 with the platen 14 so that upward swinging of the handle 18 causes upward displacement of the platen. In order to move the platen 14 downwardly against the card C on supporting surface 13 during reading of the card, the reader 11 may further include a spring 21 interposed between the platen 14 and frame 17. The reader 11 may further have conventional devices (not shown) for accurately locating the card C on surface 13 and for preventing operation of the reader except when a card is correctly located on the supporting surface.

The contact-pin assembly 10 includes contact pins 22 corresponding in number and location to all of the possible locations of perforations or punched holes provided in the card C for symbolizing the information or data to be read, and the contact pins are yieldably urged to normal positions where the upper ends thereof project a small distance above the supporting surface 13. Thus, when the platen 14 is moved downwardly against a card C on supporting surface 13, as on FIG. 2, those contact pins 22 which register with perforations or punched holes P of the card extend therethrough and contact a printed circuit or conductive layer 23 provided on the lower surface of the platen, while those contact pins which do not register with perforations of the card are depressed so that their upper ends lie flush with the supporting surface 13. The contact pins 22 which. extend through perforations of the card into contact with the printed circuit or conductive layer 23 on the platen complete corresponding electrical circuits to which they are connected by conductors 24 and 25 (FIG. 1), thereby to control the programming or operation of an associated machine or for feeding pulses corresponding to the read or sensed information to an associated computer or the like, which associated machine or computer is schematically indicated at 26.

In accordance with the present invention, the mounting for the pins 22 of contact-pin assembly 10 includes a housing 27 of insulating material, for example, phenolicresin-impregnated linen laminate or epoxy-resin glass cloth laminate, having opposed parallel, spaced-apart walls 28 and 29, such as at the top and bottom thereof, and a continuous side wall 30 extending around the periphery of the housing 27. The side wall 30 defines seats for the edges of the walls 28 and 29 on which the latter are cementitiously secured. The opposed parallel walls 28 and 29 are formed with aligned bores 31 and 32, respectively, disposed at the desired locations of the contact pins, and which are preferably provided with relatively small and large diameters, as shown on FIG. 4.

Each of the contact pins 22 preferably has a portion 33 of relatively large diameter which is axially slidable in the related bore 32 and a relatively smaller diameter tip 34 extending axially from one end of the portion 33 and being slidable in the related bore 3. It will be apparent that a shoulder is defined between the portion 33 and tip 34 of the contact pin, and the length of the tip 34 is slightly greater than the thickness of Wall 28. Thus, when the shoulder 35 of a contact pin bears against the inner or lower surface of wall 28, the tip 34 projects beyond the outer surface of wall 28 by a distance d which is at least as large as the thickness of the card C to be with a diametrical opening 36 to receive, and have soldered therein the associated wire or conductor 25 of the electrical circuitry.

The assembly 10 is completed by a body 37 of molded elastomeric material filling the interior of the housing 27. and closely adhering around the contact pins 22 in the latter and yieldably resisting axial displacement of the contact pins 22 from their normal positions where the shoulders 35 thereof bear against the inner or lower surface of the wall 28 and thus have their ends or tips 34 projecting the relatively small distance a beyond the up per or outer surface of wall 28. In a practical embodiment of the invention, it has been found suitabletoform 1 the body 37 of a rubber having a Dur'ometer hardness of about 45.

In order to ensure that axial movement of each of the pins 22 away from its normal position is accompanied by elastic deformation of the adjacent portions of the elastomeric body 37, and hence yieldably resisted by the latter,

the portion 33 of each contact pin disposed between walls 28 and 29 of the housing is preferably formed with crosssectional configurations that are non-uniform along the length of the pin and therefore lock the contact pin within the molded body. For example, each contact pin 22 may be provided with circumferentially extending grooves 38 (FIGS. 2, 4 and 6) at axially spaced apart locations, and the body 37 is molded into such grooves to achieve locking engagement of the molded elastomeric body with the several contact pins.

Alternatively, as shown on FIG. 7, the portion 33a of a contact pin 22a having a tip 341: extending from one end may be formed with axially spaced apart, radial flanges 38a which also serve to achieve locking engagement of the contact pin within the elastomeric body when the latter is molded around the flanges 38a. When the contact pins have flanges 38a, as on FIG. 7, such pins are initially inserted in the bores 32 of bottom wall 29 while the top wall 28 is separated from side wall 30, and, thereafter, the top wall 28 is applied with the tips 34a being received in bores 31.

A still further modification of a contact pin 22b is illustrated in FIG. 8, wherein the portion 33b of the contact pin having a tip 3412 at one end is formed with an axially arranged series of annular serrations 38b extending therearound for secure bonding with the elastomeric body 37.

Although the contact pin assembly 10 has been described above as applied to a punched-card reader, such contact pin assembly can be similarly applied to a device for reading or sensingthe locations of conductive markings M on a card or sheet C, as shown on FIG. 3. The conductive markings M may be applied to the card C by means of a conventional electrographic pencil of low clay content, and are engageable by adjacent contact pins 22 of the assembly 10 upon lowering of the platen 14 so that electrical circuits connected with adjacent contact pins are completed through the conductive markings engaged by the latter. In the latter case, the resilient mounting of the contact pins 22 by the elastomeric body 37 ensures proper contact of the pins with conductive markings at the corresponding locations on the card C notwithstanding surface variations of the platen or variations in the thickness of the card or of the applied conductive markings.

In producing the above described contact-pin assembly 10 in accordance with this invention, the housing 27 is provided with one or more openings 39 (FIGS. 1, 4, 5 and 6) in the side wall 30 thereof, and the housing is disposed so that the openings 39 are uppermost, as shown on FIG. 4. Then the contact pins 22 are inserted through the bores 32 of wall 29 and through the aligned bores 31 of wall 28 until the shoulder 35 of each contact pin engages against the inner surface of wall 28 so as to axially locate the contact pins with respect to the housing. After all of the contact pins have been thus located in the housing 27, a liquid latex or rubber, which may, for example, be the silicone rubber material available under the designation RTV from Dow Corning Company, is poured into the housing 27 through the opening or openings 37 until the liquid latex material rises in the opening or openings 39, as shown on FIG. 6, thereby ensuring that the interior of the housing 27 is completely filled. When the liquid latex material hardens or sets within the housing 27, the resulting elastomeric body 37 closely adheres around the contact pins 22 within the housing and, by reason of the non-uniform cross-sectional areas along the contact pins, a firm bond is achieved between the latter and the elastomeric body, as previously described.

It will be apparent that the above described contact pin assembly and the method of manufacturing the latter simplify and facilitate the production of contactpin assemblies having large numbers of contacts, and wherein such contacts are capable of individual axial displacement from normal positions at which they are resiliently retained.

Although illustrative embodiments of the invention have been described in detail herein with reference to the accompanying drawing, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claim.

What is claimed is:

A contact pin assembly for a punched card reader or the like, comprising a housing of insulatingmaterial including spaced, opposed walls, one of said walls having a plurality of spaced-apart bores of relatively small diameter and the other of said walls having an equal number of bores of relatively large diameter aligned with said small-diameter bores, a plurality of contact pins each having an overall length substantially greater than the distance between the outer surfaces of said opposed walls of the housing, each of said contact pins including a relatively large-diameter portion slidable in a bore of said other wall and a relatively small-diameter tip slidable in the aligned bore of said one wall with a radial shoulder between said portion and said tip, the length of said tip being only slightly greater than the thickness of said one wall so that, when said shoulder engages said one wall, the end of said tip projects a small distance beyond said one wall while said portion of the contact pin projects beyond said other wall, each of.

said contact pins further having non-uniform crosssections along a length of said portion between said Walls, and a molded body of elastomeric material filling said housing and closely conforming to said non-uniform cross-sections of the pins in the housing to yieldably resist axial displacement of each pin from a normal postion where said shoulder of the pin engages said one wall of the housing.

References Cited by the Examiner UNITED STATES PATENTS 546,471 9/1895 Neher 339-61 2,577,005 12/ 1951 Giacomo 264272 2,688,735 9/1954 Hubbell 3396l 2,761,111 8/1956 Klostermann 33994 X 2,903,529 9/1959 Hanthorn 200-46 2,934,792 5/1960 Harrington 264-272 3,002,169 9/1961 Kamm 339-18 JOSEPH D. SEERS, Primary Examiner.

ALFRED S. TRASK, Examiner. 

